Lag-responsive protection device



April 1951 I J. v. v. ELSWORTH Z,548,@0

LAG-RESPONSIVE PROTECTION DEVICE Filed July 1, 1949 g STRAIGHT AIK'PIPE BRAKE PIPE.

Zinneufor JohnVV Elsworrh Patented Apr. l0, 1 951 reins LAG-RESPONSIVE PROTECTION DEVICE John Van Varick Elsworth, Watertown, N. Y., as-

signor to The New York Air Brake Company, a corporation of New Jersey Application luly 1, 1949, Serial No. 102,615

2 Claims. 1

This invention relates to air brakes and particularly to safety systems for electro-pneumatic brakes. As a basis for disclosing the principle of the invention it will be described as applied to the 24-RL brake which is a commercial standard familiar to persons skilled in the art.

Basically this is a dual brake system, in which a complete automatic brake system and a complete electro-pneumatic straight-air system exist side by side throughout the train. They operate the same brake cylinders through the same relays. They are controlled by the same engineers brake valve, which may be set to operate the straight-air system or the automatic system simply by shifting a two-position selector.

A few characteristics are of present importance, and will be mentioned. The automatic brake pipe retains all its usual characteristics. Hence, a break-in-two will inevitably cause an emergency application. This major safety factor is always present. Moreover, no matter how the selector is set, the engineers brake valve always has one and the same emergency position, which will produce an automatic emergency application. Hence, the second major safety factor, characteristic of automatic operation, is always available, and available in the position used since the adoption of the equalizing discharge valve. Both major safety characteristics of automatic braking bein always present, and in no way dependent on any electrical function or straightair function, the system loses nothing by the presence of the electro-pneumatic straight-air system.

There are, however, psychological possibilities which it is desirable to take into account, tomeet and guard against human failure. The straightair pipe is divided into car length units by chokes, though it is connected continuously throughout the train. The pressure in each unit is controlled by an electrically actuated inlet valve and and electrically actuated discharge valve. All such units are controlled by a master controller located at the head of the train. Since it is impracticable to operate the electrical part of the system on a closed circuit basis, the electrical part of the system cannot have a fail safe characteristic, and since the car-lengths of the straight-air pipe are semi-isolated, units comprising more than one car, cannot be properly r controlled by adjacent cars, in the event of failure of some electrically operated valve.

Trains equipped with the 24-RL brake are operated on the straight-air principle under normal conditions. The engineers brake valve is set to establish a desired pressure in the control pipe. This pressure puts the master controller into action, and the latter through electrically actuated application and release valves establishes a related pressure in the straight-air pipe. The pressure so established exercises a follow-up or neutralizineffect on the master controller, so that establishment of the desired straight-air pipe pressure puts the master controller in balance, whereupon its action ceases.

In another application, Ser. No. 100,928, filed June 23, 1949, which issued October 31, 1950, as Patent No. 2,527,920, I have described and claimed a safety device which becomes active upon abnormal functioning of the master controller. If release magnet valves fail to close or application magnet valves do not open or if the straight-air pipe is broken or leaks, the master controller will cycle, i. e. operate repeatedly in its automatic elfort to establish straight-air pipe pressure. According to that invention cycling of the master controller, if it occurs to an extent indicating serious derangement, will cause a service application of the brakes on the automatic principle.

The present invention serves to produce a similar application if, when control pipe pressure rises, straight-air pipe pressure (at or near the master controller) lags unduly behind control pipe pressure.

This scheme can be used independently of the one in the prior application but since its functions are to an extent complementary, and since it can operate through or by the aid of components used in the other scheme, it will be here described as incorporated with the other scheme.

Only so much of the 24-RL brake equipment as is necessary to a disclosure will be here described. A complete understandin of the system can be had from The New York Air Brake Companys Instruction Pamphlet No. 59 dated May 1948, a copy of which is of record in the file of my prior application, above identified.

A preferred embodiment of the inventionwill now be described by reference to the accompany ing drawing in which the single figure i a diagram, partly sectional showing the safety devices of my prior application and of the present invention each associated with a 24-RL brake system through a single electrically operated valve forming a part of both safety devices.

The brake system and the safety device of my prior application will first be described. The engineers brake valve is indicated in elevation at l 0 and, as is well known, includes a service appli- U cation valve in the housing H. The function of this valve is to produce under certain conditions a full service application through the automatic side of the system. The engineers brake valve is convertible for operation selectively on the straight-air principle and the automatic principle, and when set for operation on the automatic principle operates the brakes by controlling the pressure in the normally charged brake pipe l2.

When set to operate on the electro-pneumatic.

straight-air principle, the engineers brake valve ID controls the pressure in the straight-air pipe I3. It does so indirectly by controlling the pressure in a control pipe l4 sometimes called the number eleven pipe because that happens to be the identifying number cast on the pipe bracket of the engineers brake valve.

The pressure in pipe l4 controls the operation of a master controller l5 which, in the example illustrated, is an electric switch controlling application and release magnet valves which in turn exercise control on the pressure in the straight air pipe. These-magnet valves are located at intervals throughout the train. One such application magnet valve'is'shown at l5 and the related-release magnet valve at IT.

The primary function of the valves l6 and H is to establish and dissipate pressure throughout the lengthof the straight-air pipe I3. In accomplishing thi s function they may operate in any of the ways known-in the art and sinc their function-is familiar, this'detail is not illustrated.

The magnet valves are controlled by the controller l5-through a three-wire circuit which extends throughout the train and comprises the B wire designated'by the-letter B, the application wire designated by-the legend App. and the release-wire designated by the legend Rel.

The-pipe i l leads to'achamber 2i at the left of an actuating diaphragm 22. The straightair pipeleads' to a chamber 23 at the right of a neutralizing or follow-up diaphragm 24. The centers of the diaphragms are connected together bya-rod 25*w'hosemotion actuates switches hereinafter mentioned. If pressure in pipe hi is raised, diaphragm- 22" moves to the right against the-resistance of a-biasing-spring 26': If pressure is immediately developed in the straight-air pipe l3 (as-should benthe case), pressure inchamber 23 balances that in 2| and the spring 25' moves the rod 25" andthe' diaphragms in the reverse direction.

Afterpressure has been established in the straight-air pipe, lowering of' the pressure in the pipe l4 and consequently in chamber 2! will: cause a further reverse movement of the diaphragms.

Rod 25 carries a collar 21 which actuates the applicationswitch' arm 28- and'the release switch arm-29' simultaneously both in circuit c1osing-di rections, The coacting contacts are so contrived that? the effect. is first to energize and close the release magnet valve HI and thereafter energize and open theapplication magnet valve It. That, of course, iswhat produces the rise of'plessure in thestraight-air pipe l3. Under lap conditions the release magnet'valveremains energized but the application magnet valve is de-energized.

It isapparent from what has just been said that if'an' engineer attempts to make an application, and-there is a break in the straight-air pipe or a serious leak therefrom, or if release magnet valves fail to function or application magnet valvesfail to; function, therewill be a disturbance of the operation. of the master controller l5. Malfunctions short of complete circuit failure (against which other safeguards are interposed), cause the master controller l5 to cycle that is, cause it to reciprocate or operate recurrently. The invention makes use of this recurrent operation or cycling to operate the service application valve in housing I l and thereby produce an automatic service application.

Operation of the service application valve is effectuated by venting a pipe 3| known in the industry as the number ten pipe. So far as here material, the venting of the pipe 3| produces an. automatic service application. The term automatic? is here used in the technical sense to mean a brake application produced by the automatic side of the system.

A winding 34 is connected between the line B and the application line so that every time the master controller I5 functions, the winding 34 is energized. The armature in the winding 34 operates a doublebeat poppet valve 35, which is biased by a coil compression spring 36 toward an exhaust seat 37'and away from an inlet seat 38. The valve 35 controls the pressure in the chamber 33 behind a combined flexible diaphragm and valve 4|.

The valve seats against an annular seat 42 and controls flow from a main reservoir connection 43 to a choke 44. Main reservoir pressure from the comiection 43 is always present in the space 45 beneath the inlet seat 38 and is also present in the annular space 46 to the left of the diaphragm 4!. The diaphragm 4| is biased toward its seat by a coil compression spring 41.

Thus, when winding 341s de-energized, diaphragm valve 4| closes but each time that wind,- ing 34 is energized the valve 4! opens. It stays open as long as the winding 34 is energized. It then supplies air to the choke 44, and this air is admitted to a small reservoir or accumulator volume 48 which is constantly vented toatmosphere through a choke 49. The sizes of the chokes 44 and 49 are So coordinated that the choke 49 will substantially dissipate pressure in the volume 48 except in cases where-winding 34 is energized with a frequency high enough to indicate derangement of the system. Pressure so developed in-the volume 48 reacts on the motor diaphragm 5101" the-normally closed pressure switch generally indicated by the numeral 52.

The source of current for the lines App, B and Rel. is typified by'the battery 53' and the switch 52 is arranged to control a circuit from this battery through the winding 54 of a magnetvalve generally indicated'at-BS. The valve 55' is biased to open by a coil compression spring 56 and when opened vents the pipe 3|. It follows that the winding 541is constantly energized'and holdsthe valve 55 closed, and that maintained closure is dependenton integrity of the circuit. The switch 52 is normally closed but will be opened if'the reservoir 48 is charged; Thus, excessive cycling of the master controller l5 causes charging of the reservoir 48 and an excessive charging rate opens the switch 52; causes thevalve 55 toopen and thus vents the pipe 3|.

Venting of the pipe 3'l'produces an automatic service application which is beyond'the control of the engineer and which warns'him that the electro-pneumatic system is seriously deranged; If he cannot discover and correct the defect; all he has to do is to convert his engineers brake valve lll'to automatic operation and proceed on the automatic principle.

While the mechanism-above described will' normally respond only to cycling of the master controller I5, a safeguard is provided against its operation in the event that the engineer initially makes a full service application which is sustained for a considerable time so that the master controller l will remain in application position for a longer period than is ordinarily the case. To prevent the safety mechanism from responding to this type of manipulation, a connection 5i leads to the lower chamber 62' of a diiferential diaphragm mechanism which includes a flexible diaphragm 53 and above the diaphragm a sec ondary chamber 64. The diaphragm is biased downward by a spring 65. A choke connection 66 leads from the branch line H to a small volume reservoir 51 and this reservoir in turn is in free communication with the chamber 64%.

From the construction just described it follows that when pipe I4 is initially put under pressure, the diaphragm 53 moves upward and remains upward for a brief period until the volume reservoir ti and the chamber 6 are charged, whereupon the spring 65 restores the diaphragm to its lower position. When the diaphragm is in its upper position it closes an electric switch 69 which is connected across the terminals of the switch 52. In this way the switch 52 is prevented for a brief time interval from interrupting the circuit through the winding 54. As a consequence there is a brief period at the start of an application in which the switch 52 is prevented from breaking the circuit through the winding 5% and causing a service application. However, this is merely a temporary suspension of the function of the switch 52 effective at the commencement of an application.

No novelty is here claimed for any of the foregoing, since it is subject matter claimed in my prior application.

The present invention provides independent means to interrupt the circuit through winding 5 and so cause an automatic service application in case of a derangement which need not cause cycling of master controller l5.

Assume that pressure is established in control pipe M and that the desired related pressure in the straight-air pipe l3 develops slowly or not at all. This could occur as a result of conditions which would not cause master controller to cycle. Hence, a second means to cause a brake application in response to this type of malfunction is desirable.

A switch ll, biased to close by spring 72 is interposed in the circuit through winding 54, and may be opened when pressure in chamber l3, above diaphragm Til, materially exceeds pressure in chamber l5 below said diaphragm.

Chamber i5 is in free communication with straight-air pipe l3. The eifective volume of chamber 13 is increased by a connected chamber '56 and the two are in restricted communication with control pipe M through choke H. A check valve 18 opens a by-pass around choke 11 when flow is toward control pipe M.

From the above construction it follows that rising pressure in control pipe id becomes effective in chamber is after a brief time lag. If pressure in straight-air pipe I3 lags behind the delayed pressure in chamber 18, switch l'i will open and ole-energize winding 5%. This causes valve 55 to vent pipe 3! and a service application results.

The application so made cannot be released unless the engineer either corrects the cause of the malfunction or converts his brake valve iii to operation on the automatic principle.

While the invention is complementary to that of the prior application, it can be used independently thereof (1. e. in a system which does not include the subject matter of the prior application).

Obviously the difierential pressure diaphragm it with its delay mechanism 7%, Ti, 18 can be variously embodied and can actuate a brake applying mechanism different from that here described.

I claim:

1. In an electro-pneumatic brake system the combination of a control pipe; means for establishing pressures therein; a normally vented straight-air pipe for controlling application and release of brakes; electrically actuated application and release valves operable to regulate pressure in the straight-air pipe; a pneumatically actuated master controller connected to control said electrically actuated valves, and arranged to be shifted in application direction by pressure establishedv in said control pipe and in the opposite direction by pressure in the straight-air pipe; automatic brake applying means arranged to operate independently of said straight-air pipe; an electrically controlled device serving when doenergized to cause said brake applying means to operate; a source of electric current; a switch biased to close; a circuit including said device, said source and said switch; a differential pressure motor subject to straight-air pipe pressure acting in a switch-closing direction and to control pipe pressure acting in a switch-opening direction; and selective means for delaying the development of rising control pipe pressure on said differential pressure motor.

2. The combination with the structure defined in claim 1, of a second normally closed switch in said circuit in series with the first switch; and means responsive to cycling of said master controller for opening said second switch.

JOHN VAN VARICK ELSWORTH.

REFERENCES CITED UNITED STATES PATENTS Name Date Hewitt June 2-1, 1938 Number 

